The immune system hosts a wide range of specific cell types including lymphocytes. Lymphocytes determine the specificity of immune reaction in a host and include two classes, the B lymphocytes, which are precursors of antibody producing cells and the T lymphocytes, which are required for certain regulatory functions such as the development of specific immune responses.
Mature T cells may be activated, i.e., by an antigen or other stimulus, to produce, for example, cytokines, biochemical signaling molecules, or receptors that further influence the fate of the T cell population.
B cells can be activated via receptors on their cell surface including B cell receptor and other accessory molecules to perform accessory cell functions, such as production of cytokines.
Monocytes/macrophages and T-cells can be activated by receptors on their cell surface and play a central role in the immune response by presenting antigen to lymphocytes and also act as accessory cells to lymphocytes by secreting numerous cytokines.
Natural killer (NK) cells have a common progenitor cell with T cells and B cells, and play a role in immune surveillance. NK cells, which comprise up to 15% of blood lymphocytes, do not express antigen receptors, and therefore do not use MHC recognition as requirement for binding to a target cell. NK cells are involved in the recognition and killing of certain tumor cells and virally infected cells. In vivo, NK cells are believed to require activation, however, in vitro, NK cells have been shown to kill some types of tumor cells without activation.
The interleukins are a family of cytokines that mediate immunological responses, including inflammation. The interleukins mediate a variety of inflammatory pathologies. Central to an immune response are T cells, which produce many cytokines and adaptive immunity to antigens. Cytokines produced by T cells have been classified as type 1 and type 2 (Kelso, A. Immun. Cell Biol. 76:300-317, 1998). Type 1 cytokines include IL-2, IFN-γ, LT-α, and are involved in inflammatory responses, viral immunity, intracellular parasite immunity and allograft rejection. Type 2 cytokines include IL-4, IL-5, IL-6, IL-10 and IL-13, and are involved in humoral responses, helminth immunity and allergic response. Shared cytokines between Type 1 and 2 include IL-3, GM-CSF and TNF-α. There is some evidence to suggest that Type 1 and Type 2 producing T cell populations preferentially migrate into different types of inflamed tissue.
The skin plays an important role in the immune system and consists of layers. The epidermis is a surface layer. Underneath the epidermis is the dermis, a layer of connective tissue. Underneath the dermis, is the hypodermis, a layer of large amounts of adipose tissue. Circulating T lymphocytes migrate to the skin under normal and inflammatory conditions. The cutaneous lymphocyte antigen (CLA) is considered a homing receptor for T cells with tropism for the skin. Santamaria-Babi, L., Eur. J. Dermatol 14:13-18, 2004.
Several diseases of the skin are known to express high levels of CLA+ T cells, including atopic dermatitis, contact dermatitis, drug-induced allergic reactions, skin-tropic viruses and viral associated pruritis, vitiligo, cutaneous T cell lymphoma, alopecia aerata, acne rosacea, acne vulgaris, prurigo nodularis, and bullous pemphigoid. There is a need to treat such skin T cell mediated diseases.
The demonstrated in vivo activities of the cytokine family illustrate the enormous clinical potential of, and need for, other cytokines, cytokine agonists, and cytokine antagonists. IL-31, a newly identified cytokine. IL-31, when over-expressed in mice, results in dermatitis-like symptoms. Both skin-homing T cells and epidermal kerationcytes have been implicated in the pathology of skin diseases in humans. The present invention addresses these needs by providing antagonists to pro-inflammatory cytokine IL-31. Such antagonists of the present invention, which may block, inhibit, reduce, antagonize or neutralize the activity of IL-31, include soluble IL-31RA receptors and neutralizing anti-IL-31 antibodies. The invention further provides uses therefor in inflammatory disease, as well as related compositions and methods.